Does anyone run CrossfireX?

[sotiris.bos]

CAREFUL! Not Crossfire, but CrossfireX. Would it be a terrible idea if i picked up a 7970 to couple with my 7950?

[DyGr00339]

CAREFUL! Not Crossfire, but CrossfireX. Would it be a terrible idea if i picked up a 7970 to couple with my 7950?

It would run like a 7950

[mvitkun]

It would run like a 7950

from what I understand the HD 7970 would still be able to use all of it's cores and maintain a higher clock speed than the HD 7950.

so the HD 7970 would be somewhat worthwhile depending on the price vs a HD 7950.

this quote is from an OC.net user that explained it pretty well.

AMD cards can work at their own specification (core, memory clocks, voltage and SP/Shaders) in Crossfire. They don't have to downclock or sync'ed, etc.

 

This example is exaggerated and over simplified with 100% perfect scaling;

 

6970 1536 shaders = Card A is faster clock per clock

6950 1408 shaders = Card B

 

In Crossfire;

 

Card A renders Frame #1 = 3ms

Card B renders Frame #2 = 4ms

Card A renders Frame #3 = 3ms

Card B .......

  

6970 + 6950 crossfire produces 2 frames/3.5ms

6970 + 6970 crossfire produces 2 frames/3.0ms

6950 + 6950 crossfire produces 2 frames/4.0ms

 

 

Edit:

 

This applies to:

 

1. 5850 + 5870

2. 6850 + 6870

3. 7950 + 7970

4. 7990 + 7970

5. Etc.

[mvitkun]

 

[sotiris.bos]

from what I understand the HD 7970 would still be able to use all of it's cores and maintain a higher clock speed than the HD 7950.

so the HD 7970 would be somewhat worthwhile depending on the price vs a HD 7950.

this quote is from an OC.net user that explained it pretty well.

But doesn't crossfire split the screen to upper and lower half and assign it to each GPU?

[mvitkun]

But doesn't crossfire split the screen to upper and downer half and assign it to each GPU?

I think you misunderstood my post.

 

all I was saying was that you would see a benefit from HD 7970 + HD 7950 crossfire over HD 7950 + HD 7950 crossfire. 

[sotiris.bos]

I think you misunderstood my post.

 

all I was saying was that you would see a benefit from HD 7970 + HD 7950 crossfire over HD 7950 + HD 7950 crossfire. 

I know but is there a higher possibility to experience screen tearing or some kind of other bugs that you wouldn't or would be less likely to with 2 identical GPUs?

[mvitkun]

I know but is there a higher possibility to experience screen tearing or some kind of other bugs that you wouldn't or would be less likely to with 2 identical GPUs?

to the best of my knowledge no.

 

your still going to have two gpu's working on rendering the same frame,that's already introducing significant latency.

the amount of latency saved by having identical gpus would most likely be negligible .